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Biomedical subjects

O Alonso

Publications and source records attributed to O Alonso.

53 records · Page 3Linked to original sources
PubMed1992

Intraventricular infusion of N-methyl-D-aspartate. 1. Acute blood-brain barrier consequences.

The purpose of this study was to document the early cerebrovascular consequences of excessive N-methyl-D-aspartate (NMDA) receptor activation. Five microliters of NMDA (100 nmol/microliters) or vehicle was infused over a 15-min period into the lateral ventricle of adult rats. The protein tracer horseradish peroxidase (HRP) was injected intravenously for blood-brain barrier (BBB) studies. The intraventricular infusion of vehicle (n = 5) caused no alterations in arterial blood pressure or microvascular damage away from the intraventricular probe tract. In contrast, NMDA infusion (n = 8) led to a gradual increase in arterial blood pressure (mean 36 mm Hg). Multifocal regions of HRP extravasation were observed bilaterally throughout the neuraxis following NMDA infusion. Sites of BBB disruption and hemorrhage included brain regions bordering ventricular spaces. In addition, isolated foci of protein extravasation were commonly detected in the cerebral cortex, thalamus, basal forebrain, septum and cerebellum. Pretreatment with the noncompetitive NMDA antagonist MK-801 (2 mg/kg) substantially reduced the BBB responses to NMDA. However, microvascular abnormalities were seen in NMDA-infused rats where blood pressure elevations were inhibited by blood removal. In addition to neurons, cerebral blood vessels are also acutely affected by NMDA receptor activation. Blockage of NMDA receptor channels following brain injury may potentially provide protection by attenuating BBB breakdown and subsequent brain edema.

Animals↗
PubMed1992

Intraventricular infusion of N-methyl-D-aspartate. 2. Acute neuronal consequences.

This study documents the ultrastructural features of acute neuronal injury following N-methyl-D-aspartate (NMDA) receptor activation. NMDA (100 nmol/microliters) or vehicle was infused over a 15-min period into the lateral ventricle of adult rats. After perfusion fixation, specimens demonstrating normal and abnormal patterns of vascular permeability to horseradish peroxidase were sampled for ultrastructural analysis. In NMDA-infused rats, brain regions exhibiting protein extravasation contained swollen dendritic profiles and abnormal neuronal perikarya. Although periventricular regions were most severely affected, parenchymal abnormalities were also detected in the cerebral cortex, septum, striatum, thalamus, hypothalamus and cerebellum. Mildly affected dendrites contained dark compact mitochondria, while in severely swollen dendrites mitochondria were enlarged with ruptured cristae. Focal sites of plasma membrane disruption were also detected within swollen dendrites. Swollen neurons commonly displayed peripheral pallor and increased numbers of cytoplasmic vacuoles. Other neurons appeared dark and shrunken, some containing disrupted mitochondria and pyknotic nuclei. Pretreatment with the NMDA antagonist MK-801 (2 mg/kg) attenuated the neuronal and dendritic alterations. In conditions where cerebrospinal fluid levels of glutamate are abnormally elevated, excessive NMDA receptor activation may lead to early vascular and neuronal complications which could work in concert to promote brain injury.

Animals↗
PubMed1991

Amphetamine promotes recovery from sensory-motor integration deficit after thrombotic infarction of the primary somatosensory rat cortex.

The present studies were undertaken to examine 1) whether d-amphetamine sulfate administered to rats well after thrombotic infarction of the vibrissal cortical barrel-field within the primary somatosensory cortex affected the rate and completeness of behavioral recovery and 2) whether a dose-response relation exists between d-amphetamine sulfate dose and recovery of function. In a learning task requiring sensory-motor integration, 41 rats were trained to perform a motor response in a T-maze consequent to the detection of a vibrissal deflection cue. Once training was complete, unilateral (n = 29) or sham (n = 12) infarction was produced by a noninvasive photochemical technique. After infarction, T-maze performance was assessed repeatedly in rats receiving 2 (n = 10) or 4 (n = 10) mg/kg d-amphetamine sulfate or saline (n = 9) 24 hours prior to testing on days 4, 6, 9, and 11. The sham-operated control rats received d-amphetamine sulfate (n = 7) or no injections (n = 5). All three infarcted groups displayed a reliable and sustained behavioral deficit in performance that was not present in the sham-operated control animals. Although the performance of each infarcted group improved over the testing sessions after the first injection, the amphetamine-treated groups improved at a faster rate than the saline-injected group. The results further demonstrated a dose-response effect, with the 4 mg/kg amphetamine group recovering to within preinfarction levels 6-8 days earlier than the 2 mg/kg amphetamine and saline-injected groups. Moreover, both amphetamine-treated groups recovered more completely than the saline-injected group. Quantification of the chronic infarct area revealed no differences among the amphetamine-treated and saline-injected groups. These data provide further evidence of the facilitatory effect of d-amphetamine sulfate on recovery from brain injury and extend this effect to the enhancement of recovery subsequent to thrombotic infarction of the primary somatosensory cortex.

Amphetamine↗
PubMed1990

Influence of amphetamine treatment on somatosensory function of the normal and infarcted rat brain.

The consequences of acute amphetamine administration on the metabolic responsiveness of the cerebral cortex to physiologic activation were studied in normal and infarcted rats. Treated rats received a 4 mg/kg intravenous injection of d-amphetamine 1 hour before unilateral vibrissae stimulation and 2-deoxyglucose study. In nontreated normal rats, metabolic activation was restricted to the major relay stations of the vibrissae-barrel circuit. In amphetamine-treated rats, stimulation-induced increased glucose utilization was widespread, including ipsilateral and contralateral cortical regions outside the barrel field circuit. For example, an 84% increase in glucose utilization above control was seen in cortical areas anterior to the barrel field region. Increased glucose utilization induced by stimulation was severely depressed in nontreated rats that had undergone infarction of the left cortical barrel field 2 weeks previously. Vibrissae stimulation failed to increase glucose utilization significantly in cortical areas remote from the infarct. In contrast, bilateral increases in glucose utilization were observed within cortical regions of treated infarcted rats. For example, a 50% increase in glucose utilization was detected in cortical areas bordering the infarct. Thus, in the normal and infarcted rat, amphetamine appears to promote alternate circuit activation--a pharmacologic property that may be advantageous for recovery after injury.

Amphetamines↗
PubMed1985

First report of bluetongue antibody in Chile.

A sample of 1,752 bovine sera collected from 99 herds throughout the Tenth Region, Chile, from March 8 to November 20, 1982, was analyzed for bluetongue (BT) antibodies using the immunodiffusion (ID) test. The prevalence of BT virus (BTV) antibody was 19.6%. Sixty-four (64.6%) herds showed at least 1 positive animal, which suggests an important antibody distribution in the area. The examination of 500 sera of sheep in 14 herds indicated the following results: 8/500 animals were positive in 5/14 of the herds.

Animals↗
PubMed1984

Regional blood flow in compression-induced brain edema in rats: effect of dietary vitamin E.

Regional cerebral blood flow (rCBF) was studied autoradiographically in a murine model of focal epidural brain compression, and the effect of vitamin E administration was investigated. Mean cortical CBF was reduced to 0.48 to 0.50 ml/gm/min following 2 or 24 hours of compression. Early (2 hours) following subsequent decompression, a mixed pattern of hypoperfusion and hyperperfusion was observed. Twenty-four hours later, rCBF heterogeneities were less marked. Comparisons among animal groups raised on vitamin E-supplemented, vitamin E-normal, and vitamin E-deficient diets 2 hours after decompression revealed marked reductions in rCBF in the previously compressed cortex of the last two groups and hyperemia of the underlying hippocampus. The vitamin E-supplemented rats showed increased flow in the previously compressed cortex. In addition, vitamin E supplementation tended to eliminate rCBF gradients between subjacent zones. These data may help explain our previous observations of the beneficial effects of vitamin E on compression-induced brain edema.

Animals↗
PubMedDate not supplied

The human cranial remains from Gran Dolina Lower Pleistocene site (Sierra de Atapuerca, Spain).

In this article we study the cranial remains of the late Lower Pleistocene human fossils from Gran Dolina (Sierra de Atapuerca, Spain), assigned to the new species Homo antecessor. The cranial remains belong to at least five individuals, both juveniles and adults. The most outstanding feature is the totally modern human morphology of the very complete face ATD6-69, representing the earliest occurrence of the modern face in the fossil record. The Gran Dolina fossils show in the face a suite of modern human apomorphies not found in earlier hominids nor in contemporary or earlier Homo erectus fossils. There are also traits in the Gran Dolina fossils shared with both Neandertals and modern humans, which reinforce the hypothesis that Neandertals and modern humans form a clade, and that the Gran Dolina fossils are a common ancestor to both lineages.

Age Determination by Teeth↗
PubMedDate not supplied

[Examination of regional limph nodes in penile carcinoma by 99M Tc-MIBI scintigraphy].

99mTc-MIBI scintigraphy has proven utility as a clinically valuable technique for the diagnosis of various primary and recurrent malignant lesions. We report the case of a 65 year old man with penile squamous cell carcinoma and clinically questionable bilateral inguinal lymph nodes. 99mTc-MIBI scan shows increased focal uptake in both groins and in the right iliac region. The patient underwent penile amputation with bilateral lymphadenectomy. Histopathologic report revealed metastatic lymph nodes in all lymphatic basins seen with 99mTc-MIBI. We conclude that this technique has the potential of supplying clinically relevant information for the diagnosis of regional extension of patients with penile carcinoma.

Aged↗
PubMedDate not supplied

[Value of radioguided surgery with dobutamine 99mTc-MIBI in persistent secondary hyperparathyroidism].

99mTc-MIBI is a radiopharmaceutical that has been successfully used for the detection of hyperfunctioning parathyroid glands and for radioguided surgery techniques. We report on the case of a 55 year old woman in hemodialysis, with secondary persistent hyperparathyroidism after total parathyroidectomy. The conventional double-phase 99mTc-MIBI parathyroid scintigraphy was negative. The study was repeated after sensibilization with intravenous low-dose dobutamine showing an area of increased focal uptake in the lower cervical region. With this finding, radioguided 99mTc-MIBI surgery was performed after dobutamine administration, using a hand held gamma probe. The technique was considered successful with the resection of parathyroid cervical tissue which was further confirmed as nodular hyperplasia. We conclude that this methodology has the potential of being a an useful tool for the intraoperative localization of remanent tissue in patients with secondary persistent/recurrent hyperparathyroidism.

Dobutamine↗
PubMedDate not supplied

Management and outcome of liver recipients with post-transplant lymphoproliferative disease.

BACKGROUND/AIMS: The possibility of development of post-transplant lymphoproliferative disease by patients receiving immunosuppressive therapy is well known. However, elective treatment and outcome remain controversial. We reviewed the management and outcome of our patients with post-transplant lymphoproliferative disease. METHODOLOGY: Records of 457 patients who underwent orthotopic liver transplantation from 1986 to 1997 were analyzed. Patients who developed post-transplant lymphoproliferative disease were reviewed retrospectively. Incidence, clinical presentation, risk factors and outcomes were examined with special emphasis on ductopenic rejection and hilum involvement. RESULTS: Eleven patients developed a post-transplant lymphoproliferative disease (2.4%). These were B-cell non-Hodgkins lymphoma, Epstein-Barr virus-associated in all cases. Five patients (45.5%) received monoclonal antibodies or antithymocyte globulin. Seven patients (63.6%) developed a lymphoproliferative disease before 9 months post-transplant and 4 recipients (36.4%) after 20 months. No late lymphomas regressed after withdrawal from immunosuppression. Six patients (54.5%) were treated with chemotherapy. Eight patients (72.7%) had a tumoral remission. Five patients (45.5%) developed chronic rejection after immunosuppressant discontinuation. Four of them died as a consequence of ductopenic rejection and retransplantation was required in another; 2 died due to graft hilum infiltration. Five patients (45.5%) are alive after a follow-up of 36.5 +/- 32 months (range: 4-77 months). CONCLUSIONS: Patients with post-transplant lymphoproliferative disease require a close follow-up in order to promptly treat conditions that could lead to death. In our series, these were more closely associated with a failing transplanted organ than with the lymphoma itself.

Adolescent↗